1. Field of the Invention
The present invention relates to fasteners with improved retaining effect in an object in which they are mounted.
2. Description of the Related Art
FIG. 1 of the drawings illustrates a conventional fastener for wood. The fastener 1 includes a plurality of spaced ridges 3 on an outer periphery of a main body 2 thereof, the ridges 3 being arranged along a helix. In use, the fastener 1 is screwed into a first piece of wood (not shown) and a bolt (not shown) is extended through a second piece of wood (not shown) and then through a groove 4 in an upper part of the fastener 1 and engaged with a screw hole (not shown) in a lower part of the fastener 1, thereby securely engaging the two pieces of woods together. It was, however, found that the fastener 1 tends to be disengaged from the first piece of wood along the engaging passage when the fastener 1 is turned or subjected to a force. As a result, the fastener could not provide the required retaining function.
It is the primary object of the present invention to provide fasteners with improved retaining effect in an object in which they are mounted.
In accordance with a first aspect of the invention, a fastener comprises a body, a plurality of spaced ridges arranged along a helix on the body, and at least one retainer formed on the body after one of the ridges. The at least one retainer extends at a greater pitch than the ridges do.
In accordance with a second aspect of the invention, a fastener comprises a main body having a plurality of spaced ridges formed on an outer periphery thereof. Each ridge extends along a direction that is parallel to a longitudinal direction of the main body. At least one of the ridges has a retainer extending in a direction that is at an angle with an extending direction of the ridge.
The retainer is at an acute angle with the ridge. The main body of the fastener includes a first end with a hexagonal groove defined therein. The main body of the fastener further includes a second end having a screw hole that is communicated with the hexagonal groove. The main body of the fastener may include an enlarged end to prevent excessive screwing of the fastener into wood. In an alternative embodiment, the fastener includes an end having a cruciform groove for engageing with a screwdriver. In another embodiment, the main body at the fastener tapers from the first end thereof toward the second end thereof. The helix may include an inclined screw-thread angle to assist in screwing of the fastener into the wood. The ridge is crescent and includes a lower first end and an upper second end. The retainer projects from the upper second end of the ridge and extends upward alone the direction that is at an angle with the extending direction of the ridge. In a further embodiment, the retainer is separated from the ridge.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.